-- Fitting a Surface with SURFIT
A new task is available in IRAF V2.10.3/V2.11 and also in the
nmisc
external package
that fits a two dimensional surface to a set of possibly irregularly
sampled points specified in a text file. This task is called
surfit and
is part of the general utilities package. The input
data points are used in
a weighted least-squares fit to a surface function; a function of two
coordinates. The type and order of the surface is up to the user. The
results of the fit can be output in three ways. The surface coefficients
and the fitted values at the input points may be written out.
Alternatively, another file of coordinates can be input, and the fitted
values at those points will be output. Finally, the surface can be sampled
in an even grid, as defined by the user, to produce an image of the
surface. This task will have uses in smoothing irregular 2D data, and
interpolating and creating smooth images of randomly sampled data. It is
intended for data with relatively low spatial frequencies and not for
creating and sampling images with high spatial frequencies.
Frank Valdes
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